Benzocaine

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Benzocaine
Benzocaine.svg
Benzocaine-from-xtal-3D-balls.png
Systematic (IUPAC) name
Ethyl 4-aminobenzoate
Clinical data
Trade namesAnbesol, Cepacol, Lanacane
AHFS/Drugs.commonograph
Pregnancy cat.C (US)
Legal statusOTC (US)
RoutesTopical
Identifiers
CAS number94-09-7 YesY
ATC codeC05AD03 D04AB04, QN01AX92, N01BA05, R02AD01
PubChemCID 2337
DrugBankDB01086
ChemSpider13854242 YesY
UNIIU3RSY48JW5 YesY
KEGGD00552 YesY
ChEBICHEBI:116735 YesY
ChEMBLCHEMBL278172 YesY
Chemical data
FormulaC9H11NO2 
Mol. mass165.189 g/mol
 YesY (what is this?)  (verify)
 
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"Americaine" redirects here. For other uses, see Americain (disambiguation).
Benzocaine
Benzocaine.svg
Benzocaine-from-xtal-3D-balls.png
Systematic (IUPAC) name
Ethyl 4-aminobenzoate
Clinical data
Trade namesAnbesol, Cepacol, Lanacane
AHFS/Drugs.commonograph
Pregnancy cat.C (US)
Legal statusOTC (US)
RoutesTopical
Identifiers
CAS number94-09-7 YesY
ATC codeC05AD03 D04AB04, QN01AX92, N01BA05, R02AD01
PubChemCID 2337
DrugBankDB01086
ChemSpider13854242 YesY
UNIIU3RSY48JW5 YesY
KEGGD00552 YesY
ChEBICHEBI:116735 YesY
ChEMBLCHEMBL278172 YesY
Chemical data
FormulaC9H11NO2 
Mol. mass165.189 g/mol
 YesY (what is this?)  (verify)

Benzocaine is a local anesthetic commonly used as a topical pain reliever or in cough drops. It is the active ingredient in many over-the-counter anesthetic ointments such as products for oral ulcers. It is also combined with antipyrine to form A/B otic drops to relieve ear pain and remove earwax.

Chemical properties[edit]

Benzocaine is the ethyl ester of p-aminobenzoic acid (PABA). It can be prepared from PABA and ethanol[1] by Fischer esterification or via the reduction of ethyl p-nitrobenzoate. Benzocaine is sparingly soluble in water; it is more soluble in dilute acids and very soluble in ethanol, chloroform and ethyl ether. The melting point of benzocaine is 88–90 °C,[2] and the boiling point is about 310 °C.[3] The density of benzocaine is 1.17 g/cm3.

History[edit]

Benzocaine was first synthesized in 1890 by the German chemist Eduard Ritsert (1859–1946),[4] in the town of Eberbach[5] and introduced to the market in 1902 under the name "Anästhesin".[6][7]

Mechanism of action[edit]

Pain is caused by the stimulation of free nerve endings. When the nerve endings are stimulated, sodium enters the neuron, causing depolarization of the nerve and subsequent initiation of an action potential. The action potential is propagated down the nerve toward the central nervous system, which interprets this as pain. Benzocaine acts to inhibit the voltage-dependent sodium channels (VDSCs) on the nerve membrane, stopping the propagation of the action potential.

Side effects[edit]

Over-application of oral anesthetics such as benzocaine can increase the risk of pulmonary aspiration by relaxing the gag-reflex and allowing regurgitated stomach contents or oral secretions to enter the airway. Applying an oral anesthetic and consuming beverages before going to bed can be particularly hazardous. The oral use of benzocaine products has been found to be a cause of methemoglobinemia, a disorder in which the amount of oxygen carried by the blood is greatly reduced. This side effect is most common in children under 2 years of age.[8]

Benzocaine may cause allergic reactions.[9][10][11][12] It is a chief allergen of Balsam of Peru, which a number of surveys have identified as being in the "top five" allergens most commonly causing patch test reactions in people referred to dermatology clinics.[13]

Other uses[edit]

Benzocaine is used as a key ingredient in numerous pharmaceuticals:

Benzocaine is commonly found, particularly in Britain, as an impurity in street cocaine. Whilst giving a numbing effect similar to cocaine on users' gums it does not actually produce the effects of cocaine. But in terms of an orally based saliva drug test benzocaine can and has been mistaken for a false positive for cocaine.[17]

References[edit]

  1. ^ Demare, Patricia; Regla, Ignacio (2012). "Synthesis of Two Local Anesthetics from Toluene: An Organic Multistep Synthesis in a Project-Oriented Laboratory Course". Journal of Chemical Education 89: 147. doi:10.1021/ed100838a. 
  2. ^ "Monographs: Pharmaceutical substances: Benzocainum – Benzocaine". The International Pharmacopoeia. Retrieved September 29, 2009. 
  3. ^ D'Ans-Lax, Taschenbuch für Chemiker und Physiker, 4. Auflage, Band 2, Springer Verlag 1982, ISBN 3-540-12263-X
  4. ^ Biography of Eduard Ritsert (in German): Deutsche Biographie: Ritsert, Eduard .
  5. ^ "100 years of Dr. Ritsert". Dr. Ritsert Pharma. Retrieved March 14, 2010. 
  6. ^ Harry Auterhoff, Lehrbuch der pharmazeutischen Chemie (Stuttgart, Germany: Wissenschaftliche Verlagsgesellschaft, 1968).
  7. ^ Ritsert, E. (1925) "Über den Werdegang des Anästhesins" (On the development of Anästhesin), Pharmazeutische Zeitung, vol. 60, pages 1006–1008. See also: Christoph Friedrich and Magdalena Klimonow, "150. Geburtstag: Eduard Ritsert und das Anaesthesin" (150th birthday: Eduard Ritsert and Anästhetsin [Benzocaine]"), Pharmazeutische Zeitung online. First published clinical study demonstrating the efficacy of benzocaine: Noorden, C. v. (1902) "Ueber para-Aminobenzoesäure-Ester als locales Anästhetikum" (On [an] ester of para-aminobenzoic acid as a local anaesthetic), Klinische Wochenschrift, vol. 39, pages 373–375.
  8. ^ "Benzocaine Topical Products: Sprays, Gels and Liquids – Risk of Methemoglobinemia". Drugs.com. Retrieved March 20, 2014. 
  9. ^ ".". Retrieved March 20, 2014. 
  10. ^ "A 10-year retrospective study on benzoca... [Am J Contact Dermat. 1999". Ncbi.nlm.nih.gov. January 24, 2014. Retrieved March 20, 2014. 
  11. ^ ".". Retrieved March 20, 2014. 
  12. ^ By  Leslie Goldman (February 5, 2008). "Go easy on medicated lotions, creams, gels". CNN. Retrieved March 20, 2014. 
  13. ^ "Contact Dermatitis: Dermatitis". Merck Manual Professional. Retrieved March 20, 2014. 
  14. ^ "'Longer-lasting' condom launched". BBC News. June 17, 2002. 
  15. ^ Garner, Dwight (December 15, 2002). "Endurance Condoms". The New York Times. 
  16. ^ Eslamian L, Borzabadi-Farahani A, Edini HZ, Badiee MR, Lynch E, Mortazavi A. (2013). "The analgesic effect of benzocaine mucoadhesive patches on orthodontic pain caused by elastomeric separators, a preliminary study.". Acta Odontol Scand. 71 (5): 1168–73. doi:10.3109/00016357.2012.757358. PMID 23301559. 
  17. ^ "Drug prices: All cut up : Cocaine is cheaper, but weaker". The Economist. August 11, 2012. 

External links[edit]